Improvement in paper-pulp digesters



'UNITED STATES PATENT OFFICE.,

WILLIAM F. LADD, oF NEW YORK, N. r.

IMPROVEMENT IN PAPER-PULP DIGESTERS.

Specification forming part of Letters Patent No. 155,836, dated October 13, 1374 5 application tiled October 20, 1873.

.To all whom it may concern:

Be it known that I, WILLIAM F. LADD, of the city, county, and State of New York, have invented a new and useful Improvement in PaperPnlp Digesters; and do hereby declare the following to be a description of my invention full, clear, and precise enough to enable those skilled in the art to which it appertains to make and use the same, reference being had to the drawing which accompanies this specification, and displays the nature of my invention. j

My invention pertains to that class which have for their object the perfection of apparatus for pulping vegetable matters in the process of paper manufacture and other kindred uses.

My invention consists of an elongated, spheroidal, egg, or pear shaped metal boiler, either wholly or in part jacketed, or provided with a coil of steam or hot-water pipes, re' volved by suitable mechanism on its minor axis upon trunnions, through which inlet and outlet pipes run, connecting within with the annular space inclosed between the boiler and the jacket, or with the system of pipes when used. At one end of this boiler is located a suitably-contrived man-hole, at the other and opposite to it, an escape-valve ot' convenient pattern.

In practice I prefer to construct my boiler with a steam or hot-water jacket, and the following is a detailed description of the whole eontrivance referred to in the accompanying drawing.

A is the boiler proper, part of which is shown removed to display the internal arrangements--practically, spheroidal is an advantageous shape. B is the jacket, a portion of which is also removed to exhibit the internal connections of the trunnions and the partial division F of the jacket-space, for the better promotion of thorough circulation of the water or steam. rlhe jacket is shown as covering only one end and about two-thirds ot' the length of the boiler, but may cover it completely, or in any fractional part greater than one-half its length.

A system of piping may be substituted for the jacket, if desired, with practically the same results.

C and C are trunnions, riveted or in any manner attached to the jacket, which balances upon them, C containing the inlet, and C' the outlet, pipes. These trunnions rest on frictionrollers, or in any fit bearing, are hollow, and provided with stuffing -box connections to keep tight, in rest or rotation, the steam inlet and outlet pipes. Through trunnion C the steam or hot water liows freely into the annular space between the boiler and jacket, and then circulates, being deflected and made to iow in descending and ascending currents by the internal partition F between the boiler and jacket, all as indicated by the arrows in the drawing. D are friction-rollers, supporting the trunnions and shown attached to solid frame-work. G ,is the filling mau-hole, through which the vegetable substance is admitted, and H au escape or outlet valve, out of which the pulp is blown. E and J are a gear and spiral, by means of which the boiler is revolved.

My mode ot" operation is as follows: The boiler being brought with the man-hole up, and the escape-valve being closed, is, through the man-hole, filled with the desired amount of straw, esparto, wood, and the like, together with the chemical solution. The man-hole is then closed and steam or hot water admitted from the source of supply through the trunnion C, allowed to circulate throughout the jaeketed space, and escape through the trunnion C', a continuous current being kept up, it' desired. The boiler is then caused to revolve either continuously or intermittently. In continuous revolution, one in five minutes suffices; or, by an alternate half-revolution, each end may be separately brought uppermost, and allowed so to remain for a few minutes.

By this means an evenly-distributed action of the chemical solution is obtained upon all portions of the vegetable matter, and a much more concentrated fsolution can be employed, acting more efi'ectively in the pulping action, even though. in smaller quantity than under the old process, when the solution was perforce weakened by the introduction into it of steam in the necessary heating. When straw and other bulky material is to be acted upon by the alkaline solution, the advantage ot' using it in concentrated state is immense, as

-the recovery of the' alkali by evaporation can be made a commercial success.

Foremost atnong the great advantages possessed by a boiler of my construction are its almost absolute indestructibility by use, and

the great economy in expense oi repairs enuring therefrom by reason of the absolute restock, or applying fire direct to the boiler.

I do not claimthe jacke/ced boiler, rotating 'upon its shorter axis, and provided with a trunnion induction for steam, which is shown in Letters Patent No. 111,851, granted February 14, 1871, to William Burr Johns.

Having thus fully described myinvention, What I claim, and desire to secure by Letters Patent of the United States, is l An elongated boiler revolving on its shorter axis, provided With a jacket having a diaphragm or partition in it, in combination with the two hollow trunnions, for the purpose of causinga circulation of the steam or hot Water into and through said jacket While the boiler revolves, substantially as described.

WM. F. LADD.

Witnesses:

E. EMBREE, E. L. EMBREE. 

